In the broadcast and video industries, coaxial, twinaxial, and triaxial cables have been relied upon heavily for transmission purposes, particular at bandwidths up to around 750 MHz. These cables could be terminated in a conventional manner with a wide range of connectors that were available from many manufacturers. One particular connector is called a xe2x80x9cTri-Loc(copyright)xe2x80x9d connector, available from Kings Electronics (http://www.kingselectronics.com). However, with the move towards high definition television (HDTV) and other applications that require higher signal transmission rates compared to the conventional transmission rates, the broadcast and video industries are, in many applications, replacing coaxial, twinaxial, and triaxial cables with a hybrid cable that comprises a combination of electrical conductors and single-mode optical fibers. These hybrid cables permit digital signal transmissions at increased transmission rates over longer distances when compared to the conventional cables. Hybrid cables are available from many manufacturers, such as Commscope (http://www.commscope.com). To keep up with the changes in the cable construction, these industries also require a connector to suitably connect these hybrid cables.
For conventional power and signal wires, typically a plug and socket arrangement is provided for connecting the wires, which are usually copper wires. Many applications require a minimal contacting relationship in order to sufficiently transfer the signal. Connection beyond the minimal contacting relationship is not necessary, because the connection is made through the circumference of the respective plug and socket. Optical fibers, however, require special connections in order to properly transfer signals.
Fiber optic cables and connectors have been used for some time in the telecommunications and broadcast industries. In fact, fiber optic cables have become the standard transmission line through which information is sent. Many different types of fiber optic cables and connectors are present in the market place. A common method of making a connection between two optical fibers is to align the fibers such that the faces of the fibers oppose one another in an abutting relationship. This relationship enables the light pulses or signal transmissions travelling along the optical fibers to be transferred across the splice. If the face of one fiber is misaligned relative to the adjacent face of the other fiber, however, light is lost and quality of transmission is affected. It is therefore extremely important for fiber optic cables to have a low-tolerance fitting between splices.
A typical hybrid cable connector and technique uses several non-reusable components and urethane potting materials to isolate, secure, and protect the optical fibers and electrical conductors within the respective male and female bodies of the connector. The problem with such a connector and technique is that the potting compound is required to make the connection structurally sound, electrically insulated, and waterproof. As a result, the potting compound has to be poured or coated over the respective lines and cured before the connection can be tested, which requires a significant amount of time. If the connection needs to be redone, however, the components that are coated with the potting compound must be thrown away and the process must start from the beginning. This can be a time consuming and wasteful exercise, particular if the connection between the optical fibers is difficult to achieve and must be repeated multiple times.
Another problem with conventional hybrid connectors and techniques is that these connectors are not serviceable in the field. More specifically, conventional hybrid connectors do not provide a method of repairing damaged optical fibers except by a machine polishing technique that typically must be performed by the manufacturer. This is particularly troublesome to the equipment operator working in an unpredictable environment. For example, if an HDTV camera operator is transmitting from an outside sporting event, and the cable connecting the camera to the transmission source is severed or damaged, conventional connectors and techniques require the operator to disconnect the hybrid cable and install a new cable. Thus, an operator is required to carry spare or backup cables in case of the above-mentioned occurrences, which adds cost and bulk to the operator""s assignment. In addition, the camera operator is required to send the severed or damaged cable (with attached connectors) to the manufacturer so that the manufacturer can repair the cable. Disadvantageously, this further adds expense and time to the operator""s activities.
Accordingly, there is a need to provide a hybrid cable connector that can be adjusted and repaired in the field without having to be completely replaced or without wasting many components. There is also a need to provide a hybrid cable connector that is easy to connect to a hybrid cable and that provides structural integrity, electrical insulation, and protection against water without the use of potting compounds.
These and other needs are provided, according to the present invention, by a hybrid cable connector capable of connecting two hybrid cables having optical fibers and electrical wires. Advantageously, the hybrid cable connector of the present invention is field serviceable, thus allowing an operator to repair a damaged or broken hybrid cable in the field of operation instead of requiring the operator to disconnect the cable and send it back to the manufacturer for repair. Specifically, the hybrid cable connector and associated technique allows for the optical fibers to be prepared and repaired by the operator using hand tools while in the field. In addition, the hybrid cable connector of the present invention provides a unique insulator lock that provides structural integrity, electrical insulation, and waterproof protection to the optical fibers and electrical wires. Thus, the hybrid cable connector of the present invention does not require the use of potting compounds or other materials which add cost, time, and complexity to the connector and associated repair methods.
In particular, the hybrid cable connector of the present invention comprises male and female portions that cooperate to connect two hybrid cables. Each portion includes an outer housing defining a passage extending axially therethrough for receiving an end of a cable. Each portion also includes an insulator device having proximal and distal ends secured within the passage of the outer housing. In one embodiment, the housing comprises a strong metallic material, although non-metallic materials may also be used. The insulator device defines six channels therethrough for receiving two optical fibers or lines, two power lines, and two audio lines. Each line is attached to a respective connection contact, such as a contact pin or ferrule. The insulator lock slidably engages the insulator device, such as by a removable snapping action, for restricting the movement of the contacts within the insulator device. A spacer is provided for further structural integrity within the housing of the male and female portions of the connector. The housings of the male and female portions include a keying feature that resembles a tongue and groove configuration. In this regard, the male and female portions are prevented from rotating relative to one another.
To connect the hybrid cable to the connector of the present invention, the power and audio lines are terminated to the respective contacts by crimping or soldering. In one embodiment, the contacts for the power and audio lines comprise a conductive material, such as beryllium copper. In one embodiment, the optical fibers or lines are terminated pursuant to assembly instructions provided by Alcoa Fujikura Telecommunications. In particular, an Alcoa Fujikura field connection kit including a publication entitled xe2x80x9cAssembly Instructions For AFL Field Master(trademark) ST Connectors Using Loctite 680 Adhesive,xe2x80x9d form No. AFM 307-130, which is expressly incorporated herein by reference, is particularly useful in preparing the optical fibers for assembly within the male and female portions of the connector. Advantageously, the Alcoa field connection kit includes ceramic ferrules that receive the optical fibers. Other ferrules and contact members are also included in the kit. Once all the optical fibers and electrical conductors have been properly prepared, they are axially inserted into the respective insulator device in a predetermined pattern that corresponds to the pattern in the opposite insulator device. A bias member or spring is provided adjacent each optical fiber for biasing the optical fiber towards the open end of the insulator device. Specifically, the spring biases the contact members and ferrules against respective stops defined by the insulator device. Thus, the spring ensures positive contact between the corresponding optical fibers from the respective male and female portions. The insulator lock slidably engages the distal end of the respective insulator device and is secured thereto by a locking interference fit, such as a snap fit, between the insulator device and the insulator lock. The spacer is slidably engaged over the hybrid cable until it is adjacent the insulator lock. The hybrid cable, which in one embodiment includes an outer conductive braid, is secured to the respective housing by a crimp ring. The crimp ring provides sufficient strength between the cable and the connector to withstand a minimum of 120 pounds of pull force. A rubber-type washer is also provided to seal the inside of the housing from the environment.
The connector according to the present invention is capable of the following minimum performance requirements:
In addition, the connector of the present invention will meet the testing requirements of Underwriters Laboratories (UL), the Canadian Standards Association (CSA), or other similar authorities appropriate to the intended use of the connector.
Thus, the hybrid cable connector of the present invention provides important advancements in the state of the art. Specifically, the connector of the present invention can be adjusted in the field without wasting components as can occur when using potting compounds and/or other conventional methods. In addition, the locking interference fit between the insulator device and the insulator lock of the present invention allows for a secure connection between the opposing optical fibers and electrical conductors of the male and female portions of the connector.